Artificial teeth



May 17, 1955 J. fD. scHwARTz 2,708,314

ARTIFICIAL TEETH Filed Nov. 4, 1952 IN ENTOR.

United States Patent O ARTIFICIAL TEETH Jacob D. Schwartz, Pittsburgh, Pa.

Application November 4, 1952, Serial No. 318,711

16 Claims. (Ci. 32-2) This invention relates to improvements in artificial teeth and dentures employing the same.

Posterior teeth, in standard use today, have cusps on their occlusal surfaces, each cusp being formed of numerous inclined planes which co-act with reciprocal inclined planes of cusps in opposing teeth to provide balanced functional occlusion in sets of co-acting upper and lower dentures. Balanced functional occluson in dentures is probably the most essential feature, to comfortable use by the wearer thereof. To achieve such a result however, by present standard methods, it is necessary to use an expensive and complicated articulator, also a face bow, and to obtain protrusive bite registrations and to coordinate the numerous inclined planes of the numerous cusps present to harmonize with the condylar inclination of the lower jaw in the particular patient for whom the set of den'ures is being constructed.

To ease the task, oft times the last molars are left out of a case and the remaining teeth articulated to obtain balanced functional occlusion of the respective dentures. This scheme however denies pressure against the tissues of the jaws in the posterior ends of the dentures where it is especially necessary for proper retention of the dentures particularly the upper denture, and at the same time removes approximately 25 percent of chewing surface and efliciency from the dentures.

W'hchever plan is pursued, the technician striving to establish balanced functional occlusion, must possess relatively considerable skill and spend much time in the process. Furthermore, after the dentures are processed into their Permanent plastic or metal bases, it is invariably found that some teeth have been displaced somewhat from the position they held in the waXed-up dentures, and because in this state they cannot be rectified by being moved bodily, painstaking labor is required to grind the numerous cuspal planes to reestablish the original v set up.

It is therefore among the objects of this invention to provide-posterior teeth with which balanced functional occlusion can be obtained, in a set of co-acting upper and lower dentures, quickly, easily, definitely and accurately without the necessity of relatively considerable skill on the part of the technician.

Another object is to provide posterior teeth with which balanced functional occclusion can be obtained using a simple hinge articulator instead of an expensive and complicated adjustable articulator.

Another object is to provide posterior teeth with which balanced functional occlusion can be obtained without the use of a face bow.

Another object is to provide posterior teeth with which balanced functional occlusion can be obtained without the labor of procuring protrusive bite relations.

Another object is to provide posterior teeth with which better retention of dentures to the tissues of the jaw may be obtained.

Another object is to provide posterior teeth with which occlusal contact extending from the first bicuspid teeth 2,7%,314 atentetl May 17, 1955 rice to the second molar teeth can be had during function of a set of co-acting upper and lower dentures.

Another object is to provide a method of harmonizing the occlusal plane, of an upper and a lower co-acting denture, with the condylar inclination of the lower jaw of a patient, in the mouth instead of on an articulator.

These and other objects will be readily observed from the following description and drawings in which like reference characters, in the various views designate the same things, and in which;

Fig. 1 shows a labial and buccal surface view of a set of full upper and full lower artificial teeth and their relation to each other, as provided in this invention,

Fg. 2 shows a buccal view of an upper and a lower jaw having full dentures rnounted thereon, and also shows the condyie of the mandible nested in the glenoid fossa, and the parallel relationship of the inclined surface of the glenoid fossa to the posterior occlusal plane of the upper and lower dentures, in the buccal aspect.

Fig. 3 shows a sectional view of the dentures shown in Figure 2 at the line E-E, looking in the direction of the arrows, which shows the horizontal plane of the posterior occlusion, in the anterior aspect, and also sectional views of the recesses in the occlusal surfaces of the posterior teeth, and

Fig. 4 shows a view of of the occlusal surfaces of a bicuspid tooth and an adjacent molar tooth, showing recesses in the occlusal surfaces of these teeth.

Referring to the drawing, the lower jaw bone 3 is called the mandible, and each of both ends 14 thereof, which are egg Shape in form, is called a condyle. When the lower jaw 3 is positioned in the head, each condyle 14 is loosely nested in a bony socket or cavity of the head, called glenoid fossa 15.

By virtue of this ball and socket arrangement, that is, of the condyles 14 in the gienoid fossa 15, the lower jaw 3 is free to move in a wide variety of planes. When the lower jaw is protruded, that is, extended forward, both condyles slide out of their respective glenoid cavities. In so doing, the condyles 14 bear against the inclined surfaces 2 of the glenoid cavities 15 and they are thus lowered or declined in Vertical direction.

Likewise, when the lower jaw returns to its retruded position, which is known as the centric position, the condyles slide up the inclined surfaces Z of their respective glenoid cavity, and they are thus raised in vertical direction.

The magnitude of the condylar inclination is the number of degrees in the angle B formed by a horizontal plane C-C and the inclinedsurface 2 of the glenoid fossa. The condylar inclination in humans ranges from approximately 10 to degrees. Condylar inclinations greater than approximately 20 degrees are considered relatively sharp inclinations.

To obtain balanced functional occlusion in the construction of sets of upper and lower cooperating dentures using posterior teeth having cusps on their occlusal surfaces, which are in standard use today, for a particular patient, it is essential that the inclined planes of the cusps of these posterior teeth, which run in the anterior-posterior direction lie substantially parallel to the inclined surfaces of the glenoid fossa. By this expedient, when the reciprocal planes of the cusps of the lower posterior teeth glide across said planes of the cusps of the upper posterior teeth, the lower denture will be declined vertically to distances which are proportional to the Vertical declines of the condyles of the lower jaw. Thus, when the patient bites edge to edge, that is, when the incisal edges of the lower anterior teeth meet the incisal edges of the upper anterior teeth as in biting food, the lower jaw moves forward and, as described above, the jaw moves downward at the condyles and carries the Vdyles, the denture bases are only parted a distance which is proportional to the downward movement of the lower jaw. If the dentures should fail to contact each other from the anterior end to the posterior end during func-V tion, there would result a lack of pressure against the soft tissues of the jaws and the dentures Would be readily displaced from their seated position on the jaws. In 'other words, the lower jaw moves forward, sideward and a combination of both directions and its moves sirnultaneously downward and upward as explained above, but by means of the inclined surfaces of the cusps of the teeth co-acting with each other, continuous contact is maintained between the upper and lower dentures throughout the entire occlusal surface during these movements, thus, the occlusion between the two dentures is balanced or adjusted to maintain continuous contact during function, and this condition is called balanced functional occlusion.

From the above description, it is evident that to obtain balanced functional occlusion, using teeth in standard use today, that is, teeth having cusps, becomes a long and laborious task requiring a good measure of skill on the part of the technician. The main reason being the fact that numerically there are present many cusps and considerably more inclined planes and the majority of these inclined planes must be oriented to the condylar inclination to obtain continuous contact between the upper and lower dentures during function of the dentures.

To overcome these disadvantages, I provide sets of posterior teeth, each tooth of which is providedwith a single fiat inclined occlusal surface and all the occlusal surfaces of a set lie in a single fiat inclined occlusal plane. Hence, in order to obtain true baianced functional occlusion, that is from side to side as well as from the first bicuspid posteriorly to the Znd molars, it is only 'necessary to orient a single occlusal plane to be in harmony with the condylar inclination of the individual Vpatient for whoni the dentures are being constructed.

However, if posterior teeth having fiat occlusal survfaces are to be placed in a single fiat occlusal plane extending from the first bicuspid tooth posteriorly to the second molar teeth and have an inclination substantially that of the condylar inclination, they must have special structural characteristics. One of the principal structural characteristics provided is an upper lst bicuspit tooth having abnorrnal length With respect to the other posterior teeth in a given set of teeth and likewise an abnorrnally short upper Znd molar tooth. Thus, by virtue of the fiat sloping occlusal surface of the individual teeth provided in the present invention plus the abnorrnally long upper lst bicuspid tooth and abnormally shortupper 2nd molar tooth, it becomes easy to quickly `and accurately Orient the occlusal plane of the denture to be substantially parallel to the condylar inclinati'on of a given patient.

In the construction of a set of full upper and full lower dentures, using posterior teeth provided in the 'present invention, I employ the following method:

After I have completed the regular initial steps of obtaining centric occlusion, Vertical dirnension and mounted the upper and lower easts, with their bite blocks in position, in an articuiator (any articulator will do, even a hinge articulator) I insert upper anterior teeth in the upper wa); bite-block, I then transfer the upper and lower wax bite-blocks to the patients mouth and position said upper anterior teeth therein to obtain suitable esthetics, following which I return the upper and lower bite-blocks to the articulator.

I then insert lower anterior teeth in the lower Wax bite-block, positioning them over the lower ridge, and having their incisal edges lying substantially in the same horizontal plane in which the incisal edges of the upper teeth lie. In other words, the lower anterior teeth are placed in back of the upper anterior teeth and the incisal edges of both upper and lower anterior teeth are at substantially the same horizontal level. I then insert upper posterior teeth provided in the present invention in temporary position, in the upper bite-block.

In accordance with the present invention, I provide upper first bicuspid teeth 4 with abnormal length while the upper 2nd bicuspid teeth 5 and the upper lst and 2nd molars, 6 and 7 respectively, are progressively shorter than said upper lst bicuspid teeth 4, the second molar teeth being abnormally short. Also, said upper teeth 4, 5, 6 and V7 are provided with fiat occlusal surfaces which slope relatively sharply upward in front to rear direction, the degree of slope, with respect to the Vertical axis, of all of said teeth being substantially the same.

fhus when the upper posterior teeth provided in the present invention are inserted into the upper wax biteblock, the upper first bicuspid teeth 4, because of their abnormal length, will extend below the incisal edges of the upper anterior teeth 10, 11 and 12, and the buccoocclusal edges of all four posterior teeth 4, 5, 6 and 7 will be colinear because each tooth is progressively shorter than its anterior adjacent tooth, their occlusal surfaces have the same upward slope and lie in a single plane, and the colinear line A- A will therefore also slope sharply upward in front to rear direction, which is all clearly shown in Figure 2.

I prefer to position the plane of occlusion-of the posterior teeth, and of each posterior tooth, with respect to its Vertical axis, horizontal in the anterior aspect.

The lower posterior teeth, provided in the present invention as shown in Figure 2, are then brought into occlusal contact with said positioned upper posterior teeth.

Referring now to Figure 2 in the drawing, it Will be noted that the occlusal plane A-A is continuous with the inclined surface of the glenoid fossa 2, and hence both angles B and B' are equal. It is not necessary that this condition be met in all cases, for obviously, if the posterior occlusal plane and the inclined surface of the glenoid fossa 2 are parallel instead, the angles which they form with the horizontal line C-C would still be equal. Referring now to the above mentioned trial dentures in which a temporary sloping occlusal plane A-A of the posterior teeth has been formed, the next step is to orient this plane into a position where it `will be substantially parallel to the patient's inclined surface 2 of the glenoid fossa. This I achieve in the following manner;

With said WaXed-up trial dentures in the patient's mouth, I have him protrude his lower jaw 3 until the incisal edges of the lower anterior teeth are directly beneath the incisal edges of the upper anterior teeth and if the incisal edges of both dentures fail to contact each other, in this position, by a distance greater than approximately one-half millimeter, I presume that the occlusal plane A-A is too steep. If the incisal edges of both dentures do contact each other in this position, the slope of the occlusal plane A-A is not steep enough. If the incisal edges of both dentures in this position, are within one-half millimeter of meeting each other, I consider the slope of the occlusal plane correct, for the time being. I therefore increase or decrease the slope of the occlusal plane until proper separation of the incisal edges is obtained. This rather small separation, of one-half millimeter or less, will be closed and the incisal edges Will .contact each other, in order that the patient may bite,

after the dentures are processed and spot grinding closes the bite.

The slope of the occlusalplane A-A can be increased or decreased by respectively lowering the upper first bicuspid teeth or raising them, secondly by raising or lowering the upper second molars, or third, by tilting the vertical axes of the upper teeth slightly forward or back- Ward, the occlusal surfaces of the lower posterior teeth are then brought into contact with the occlusal surfaces of the upper teeth in their new position. To increase the accuracy and verify my findings, I follow the above procedure with registration of carbon spot markings on the occlusal surfaces of the upper and lower teeth while they are closed or clenched on carbon paper. The same procedure is employed after the dentures are processed as explained in the following paragraphs.

After the dentures are processed, some changes invariably occur in the articulation. To correct any discrepancy, the dentures are placed in the patient's niouth, and then, using carbon paper between the teeth of the dentures while in clenched or closed position, protrusive, and side to side movements are made to register, by carbon marks, areas on the posterior teeth of premature content. If these premature contacts occur on the upper and lower second molars, it usually indicates that the slope of the occlusal plane is too steep and spot grinding of the carbon marks registration should be done on the lower molars, to lessen the slope. If premature contacts are observed in the bicuspid areas, it indicates that the occlusal slope is not sufiiciently steep and spot gn'nding of the carbon marks registration should be done on the lower bicuspids to increase the slope. At the same time, the patient should be consulted to find whether he feels greater pressure on the rear molars or forward bicuspids and also whether one side contacts prior to the other and his reactions should be coordinated with the carbon marks registration. After these adjustments are completed, it will be found that the dentures will be in true balanced functional occlusion from side to side and extending from the first bicuspids posteriorly to the second molars.

It is to be noted at this point that because of the novel construction and arrangement of the teeth provided in the present invention, it becornes unnecessary in obtaining balanced functional occlusion to register protrusive bite relations in wax bite-blocks, nor to use expensive and complicated adjustable articulators, as is necessary in cases where teeth in standard use today are employed. It is clearly evident that when the teeth provided in the present invention are used, remarkable accurate results can easily and quicldy be obtained with an inexpensive hinge articulator. Then, as is well known in the art, when balanced functional occlusion is present, the dentures will be stable during function, and thus by the avoidance of the familar rocking of unbalanced dentures, there will be a better adaptation of the dentures to the soft tissues of the jaws with the consequent better retention of those dentures to their respective jaws.

To aid in eflicient chewing in the present invention, I provide each tooth, on its occlusal surface, with one or more recesses 8, which thereby reduces the occlusal surface to Cutting edges 9. The recesses 8 shown in the drawing are a preferred form, other forms may be used, for example, diagonal ridges may be provided, the only requirement being that the occlusal extremities of the cutting edges lie in a flate plane.

In Figure 1, it will be observed that the incisal edges of the anterior teeth 10, 11, 12 lie in a plane which is substantally parallel to the occlusal plane A--A of the posterior teeth. While this arrangement of parallel planes is not entirely necessary, I have obtained better esthetics and greater chewing efliciency by this expediency.

In Figure 3 which shows a sectional view through the posterior teeth in the anterior aspect, of the two coacting dentures shown in Figure 2, it will be noted that the occlusal surfaces of the teeth and the occlusal plane D D are substantially horizontal. When teeth in standard use today are employed, uslally the buccal cusps of the upper posterior teeth are made shorter than the lingual cusps,

and in the lower posterior teeth the lingual cusps are made shorter than the buccal cusps, on the assumption that the lower jaw in its lateral motions, travels through an arc. In practical experience with teeth provided in this invention and after considerable research, I have obtained Superior results when the occlusal plane of the posterior teeth and of each tooth are horizontal, in the anterior aspect, as is shown in the drawing at Figure 3.

The teeth may be constructed individually or in blocks and may be constructed of porcelain, plastics or other suitable material. Also, the teeth provided in the present invention may be used with equal advantage in both partial and full cases.

Teeth which are abnormally long, can be described in the following manner.

The total width of four natural upper posterior teeth on either side of the upper jaw, that is, the lst and 2nd bicuspids and the lst and Znd molars range from 29 to 34 millimeters. To simulate natural teeth, which they replace, artificial teeth alseo have widths for the above mentioned four posterior teeth ranging from 29 to 34 millimeters. Each of the categories, that is from total widths of 29 to 34 millimeters are made in three lengths, viz; long, medium and short. Medium length being the average length, long being longer and short being shorter than average length and the lengths of these teeth in the several width categories are proportional to their respective widths. For example a long lst bicuspid tooth in the 29 millimeter category will be shorter than a long lst bicuspid tooth in the 34 millimeter category. Furthermore, if an upper lst bicuspid tooth in the 29 millimeter category were as long, for example, as an upper lst bicuspid tooth in the 34 millimeter category, its length would be out of proportion to its width and would obviously be abnorrnally long. Also in a single category, for example, in upper posterior teeth 29 millimeter width, of the short Classification, if the lst bicuspid tooth of this set were replaced with the upper lst bicuspid tooth of an upper 29 millimeter set of the longclassification, the long bicuspid tooth would be out of proportion with the rest of the teeth of the set and would therefore obviously be abnormally long.

Having described the invention in one of its preferred forms, it being clearly understood that other designs and constructions may be made without departing from the spirit of the invention, I claim:

l. In a set of upper and lower complementary dentures including anterior and posterior teeth, a cutting edge, to aid in chewing, provided on the occlusal area of each of said posterior teeth, the occlusal extrernity of said Cutting edge lying in a fiat occlusal plane, said plane, with respect to the Vertical axis of the tooth, slopng upward in anterior to posterior direction and being substantially at right angles in the anterior aspect, all of said posterior teeth lying in a single fiat occlusal plane, said plane lying substantally at right angles to the Vertical axes of said upper posterior teeth in the anterior aspect, and sloping upward in the anterior to posterior direction, the incisal edges of the upper anterior teeth also lying in a fiat plane, said plane being located above and substantially parallel to said occlusal plane, and the foremost upper bicuspid tooth on each side of said upper denture having abnormal length with respect to said other posterior teeth.

2. In a set of upper and lower complementary dentures including anterior and posterior teeth, a cutting edge, to aid in chewing, provided on the occlusal area of each of said posterior teeth, the occlusal extremity of said cutting edge lying in a fiat occlusal plane, said plane, with respect to the Vertical axis of the tooth, sloping upward in anterior to posterior direction and being substantially at right angles in the anterior aspect, all of said posterior teeth lying in a single flat occlusal plane, said plane lying substantially at right angles to the Vertical axes of said upper posterior teeth in the anterior aspect, and sloping 7 upward in the anterior to posterior direction, the incisal edges of the upper anterior teeth being located above said occlusal plane, and the forernost upper bicuspid tooth on each side of said upper denture having abnormal length with respect to said other posterior teeth.

3. In a set of artificial posterior teeth comprising at least two upper and two compiernentary lower teeth, each of said teeth being provided with a cutting edge, to aid in chewing, on its occlusal area, the occlusal eX- trernity of said eutting edge lying in a fiat occlusal plane, said plane, with respect to the Vertical axis of the tooth, sloping upward in the anterior to posterior direction and being substantially at right angles in the anterior aspect, the occlusal surfaces of all of said teeth lying in a single flat occlusal plane and the forernost teeth of said upper teeth having abnormal length with respec. to the other teeth in said set of upper and lower teeth.

4. In a set of artificial upper posterior teeth comprising an upper bicuspid tooth and other posterior teeth which are normally used distally thereto, said bicuspid tooth having abnormal length, with respect to said other posterior teeth, each tooth of said set being provided on its occlusal area with a cutting edge, to aid in chewing, the occlusal extrernity of said cutting edge lying in a fiat occlusal plane, said plane, with respect to the Vertical axis of the tooth, sloping upward in the anterior to posterior direction and being substantially at right angles in the anterior aspect, and the occlusal surfaces of all of said teeth lying in a single flat occlusal plane.

5. In an artficial upper bicusrpid tooth, a Cutting edge, to aid in chewing, provided on its occlusal area, the occlusal extrernity of said cutting edge lying in a flat oeclusal plane, said plane, with respect to the Vertical axis of the tooth, lying substantially at right angles in the anterior aspect and sloping upward in the rnesial to distal direction from approximately 20 degrees to 45 degrees,

i said tooth having abnormal length with respect to its a first and second bicuspid and a first and second molar -2f5= teeth, each of said teeth having a Cutting edge on its occlusal area, to aid in chewing, the occlusal extremit'y of said Cutting edge lying in a flat occlusal plane, said plane, with respect to the Vertical aXis of the tooth, sloping upward in the anterior to posterior direction and being substantially at right angles theretorin the anterior aspect, the occlusal surfaces of all of said teeth lying in a single flat occlusal plane and having their bucco-occlusal edges colinear, said first bicuspid tooth being abnormally long with respect to the rest of the teeth in said set, the second bicuspid, first and second molars respectively, being progressively shorter than its anteriorly adjacent tooth and the second molar being abnorrnally short with respect to the rest of the teeth in said set.

7. In an artificial upper molar tooth, a cutting edge,

to aid in chewing, provided on its occlusal area, the occlusal extremity of said cutting edge lying in a flat occlusal plane, said plane, with respect to the Vertical axis of the tooth, lying substantially at right angles in the anterior aspect and sloping upward in the mesial to distai direction from approximately 20 degrees to 45 degrees, said tooth being abnorrnally short with respect to its other dimensions.

8. In a set of artificial upper posterior teeth comprising a first and second bicuspid and a first and second rnolar teeth, each of its said teeth having a Cutting edge on its occlusal area, to aid in chewing, the occlusal extrernity of said cutting edge lying in a flat occlusal plane, said plane, with respect to the Vertical axis of the tooth, sloping upward in the anterior to posterior direction and being substantially at right angles thereto in the anterior aspect, the occlusal surfaces of all of said teeth lying in a single flat occlusal plane and having their bucco-occlusal edges colnear, said second bicuspid, first and second molars respectively, being progressively shorter than its anteriorly adjacent tooth and the second molar being abnorrnally short with respect to the rest of the teeth in said set.

9. The method of arranging teeth in a set of full upper and full lower artificial dentures employing posterior teeth each of which has its occlusal extremity lying in a substantially flat plane, which cornprises the steps of placing the incisal edges of the anterior teeth in a flat plane, said plane being substantially horizontal in the anterior aspect and sloping'upward in anterior to posterior direction, then placing the occlusal surfaces of the posterior teeth in a separate flat plane, said posterior occlusal plane being substantially parallel to and located below said plane of said incisal edges.

it). The method of arranging teeth in full upper and lower wax bite-bloc. s for use in making a set of full upper and lower artifical dentures, ernploying posterior teeth each of which has its occlusal extren'iity lying in a substantially flat plane, which comprises inserting upper and lower anterior teeth into said upper and lower wax biteblocks, placing their incisal edges in a single flat plane, then inserting the posterior teeth into said full upper and lower Wax bite-blocks, placing their occlusal surfaces in a single fiat occlusal plane, said occlusal plane being substantially horizontal in the anterior aspect and sloping downwardly in posterior to anterior direction, the anterior end of said occlusal plane being located below the incisal edgcs of said upper and lower anterior teeth.

References Cted in the file of this patent UNITED STATES PATENTS 368,492 Robinson Aug. 16, 1887 2,075,556 Swenson Mar. 30, 1937 2,l4l,487 Pleasure Dec. 27, 1938 

